Press

ABSTRACT

A press comprising a press frame formed of a lower yoke and an upper yoke and intermediate members for interconnecting said lower yoke with said upper yoke. Further, a plurality of preloaded tensioning cables, apart from the aforementioned intermediate members, serve to hold together both of said yokes.

United States Patent Blaser 1 1 Feb. 22, 1972 [54] PRESS 3,064,558 11/1962 Von Platen ..l00/2l4 3,465,669 9/1969 Doudet ....l00/214 [721 immor- Hmy Oensmgem swltzeland 3,508,429 4/1970 Staples 100/214 x [73] Assignee: Von Roll AG, Gerlafingen, Switzerland Primary Examiner-Billy J. W1lh1te [22] Filed: Mar. 23, 1970 Attorney-Werner W. Kleeman [21] Appl. No.: 21,663

[57] ABSTRACT [30] Foreign Application Priority Data A press compnslng a press frame formed of a lower yoke and Mar. 24, 1969 Switzerland ..4395/69 an upper yoke and intermediate members for interconnecting said lower yoke with said upper yoke. Further, a plurality of [52] U.S. Cl ..100/2l4, 29/452 preloaded tensioning cables, apart from the aforementioned [51] 1nt.C1 ..B30b 15/28 intermediate members, serve to hold together both of said [58] Field ofSearch..... ....72/455,456; 100/214; 29/404, Y

[56] References Cited 5 Claims, 4 Drawing Figures UNITED STATES PATENTS 3,030,879 4/1962 Lasko ..1 00/214 X PATENTEDFEBZE I972 3.643.592

sum 1 [IF 3 INVENTOR M Adumm/ ATTORNEY PAIENTEI] FEB 2 2 I972 SHEEI 3 OF 3 Fig. 4

INVENTOR f AAW/ 8/4354 BY m 0% M ATTORNEY PRESS BACKGROUND OF THE INVENTION The present invention relates to a new and improved press which is of the type containing a lower yoke or crossbar and an upper yoke or crossbar which are interconnected with one another by intermediate members, and wherein these components form the press frame unit.

Presses of this general type are already well known to the art. According to a first embodiment of known press construction, the intermediate members consist of massive columns, and the yoke members or crossbars are secured to such columns with the aid of threaded nut members.

According to another prior art construction, the intermediate members are frame components which are connected with the yokes in suitable fashion.

Both of the prior art constructions heretofore described possess the drawback that upon loading they are subjected to relatively large deformations, since generally an overdimensioning in consideration of small deformations is not possible because of economical reasons as well as also space requirements.

Now, in order to reduce the deformations occurring at a press, a construction of press frame has become known which is especially used in deep drawing presses and plastic presses, wherein, the components interconnecting the yokes or crossbars are preloaded. To this end, apart from the components which take up the tension forces, such as for instance the columns, there are arranged intermediate members against which the yokes bear during pretensioning and which tend to compress together such intermediate members.

There has been found that with this construction, by virtue of pretensioning of the columns, there is indeed achieved a reduction of the deformations, yet the attainable pretensioning or preloading is relatively small. This is because exceptionally large tension forces have to be provided in order to pretension or preload the columns with relatively low values. Therefore, this solution is still relatively unsatisfactory since the alternating load which occurs during operation between loading and unloading is relatively large. Apart from the foregoing, the columns and the intermediate members constitute heavy, bulky components and, therefore, require correspondingly high transportation costs. Furthermore, as already mentioned, the assembly and, in particular, the application ofthc pretensioning force is difficult to carry out.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide an improved press construction which effectively overcomes the aforementioned drawbacks of the prior art.

Another, and more specific object of the present invention relates to the provision of an improved press having a press frame, the components of which are smaller than those of the known presses and which can be mounted and pretensioned or preloaded in a much more simple way.

Now. in order to implement these and still further objects of the invention. which will become more readily apparent as the description proceeds, the inventive press is manifested by the features that apart from the intermediate members there are provided a plurality of preloaded tensioning cables which hold together both yokes or crossbars.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above, will become apparent, when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a simplified schematic representation of a preferred embodiment of press frame of a press, partially shown in sectional view;

FIG. 2 is a cross-sectional view, on an enlarged scale, of the press construction shown in FIG. 1, taken substantially along the line |l-llthereof;

FIG. 3 is a graph which illustrates the load conditions as a function of elongation for a known construction of press and for the inventive construction; and

FIG. 4 is a horizontal fragmentary sectional view through a column member of the press depicting the guide means for the movable press punch.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawings, in FIG. 1 there is depicted an exemplary embodiment of inventive press which will be seen to comprise the upper yoke or crossbar l and the lower yoke or crossbar 2, such press representing, for instance, a hydraulic press. At the upper yoke member 1 there is arranged a fixed press punch 4, whereas the movable press punch 3 is secured to a nonvisible press piston which is arranged in the press cylinder 5 mounted at the lower yoke or crossbar 2.

Continuing, it will be seen that hollow column members 6 are arranged between both of the yoke or crossbar members 1 and 2. The respective ends of these hollow column members 6 are guided in recessed portions 7 and 8 of the yokes 2 and 1, respectively. Within the internal compartments or spaces 10 of the hollow columns 6 there are arranged a number of tensioning cables 9 which extend through openings 11 and 12 provided at the yokes 2 and 1, respectively. The diameter of these openings 11 and 12 substantially corresponds to that of the inner compartment 10 of the hollow column members 6.

Furthermore, it will be recognized that the tensioning cables 9 are retained in tensioning plate members 13 and 14 which are arranged at the outside of the yoke members or crossbars 1 and 2 respectively. These tensioning plate members 13 and 14 are equipped with a number of at least partially conical bores 15one such bore for each tensioning cable 9which serve for receiving nonillustrated tensioning sleeve members by means of which the preloaded cables 9 can be retained in their preloaded position. The ends of the tensioning cables 9 extend past the tensioning plate members 13 and 14 in order that they can be engaged for the purpose of preloading or pretensioning them.

During the assembly ofa press of the type shown in FIG. 1, and after both yoke members 1, 2 and the intermediate members, namely the hollow column members 6 are assembled together, then, the tensioning cables 9 are advantageously individually drawn in through the column members. After all of these cables 9 are drawn through the hollow column members 6, then these cables are preloaded or tensioned in succession until there is attained the predesired preloading value. This technique is especially useful during the assembly of large presses with very strong pretensioning cables, since to preload or tension an individual tensioning cable the tensioning mechanism which is used can be dimensioned to be much smaller than if all of the tensioning cables had to be simultaneously preloaded or tensioned collectively.

The simultaneous preloading of the tensioning cables comes under consideration for smaller presses and also for hydraulic presses of optional size. When dealing with hydraulic presses it is possible to utilize the press cylinder for carrying out the preloading or tensioning operation, in that the press piston presses against the oppositely situated yoke or crossbar member. As a result, a gap appears between the yoke and the intermediate members into which suitable insert members can be placed which retain the preloading after relieving the press cylinder.

In contrast to the column constructions of the prior art presses, the embodiment of inventive press utilizing preloading or tensioning cables is more economical and simpler to assemble since the heavy columns are dispensed with. This also results in noteworthy advantages with respect to transportation costs. Furthermore, the preloading operation is simpler and can be carried out with much smaller preloading devices since in each instance only a single cable is tensioned.

FIG. 3 graphically illustrates the advantages of an inventive press which has been preloaded with preloading or tensioning cables in contrast to a prior art column construction of press. Hence, in this figure there is shown under the graph portion (a) a prior art column construction press and under the graph portion (b) an embodiment of inventive press utilizing preloading or tensioning cables. Along the ordinate of the graph there is plotted the load or load reaction and along the abscissa the changes in length of'the corresponding components, and wherein:

S represents load-degree of elongation of the column T represents load-degree of elongation of the components which are clamped together I P represents the maximum. press force P represents the load of the preloading cable during change of the press force from O to P V represents the preloading force 7 V,,,,,, represents the smallest preloading force.

From this graph it will be apparent that the preloading cables can be preloaded much more intensely than the columns of the prior art column construction presses. Furthermore, the elongation for the preloaded cables is considerably greater ,than with the column constructions. Now, if the press force changes from O to P, then, the loading of the preloading or tensioning cables and the columns only changes by the amount P,. This value, which represents the greatest amplitude of the alternating load acting upon the tensioning cables or the columns, is considerably larger for the column construction-type presses than with the inventive press construction having preloaded cables, so that for the column construction-type presses the danger of permanent rupture is increased.

A further advantage of the embodiment of inventive press having preloaded cables resides in the fact that also if there is any relaxation, for instance due to settling of the material, the preloading only slightly changes, whereas with the column construction-type press of the prior art with their small elongation the danger exists that the preloading will be considerably reduced or even, in fact, completely nullified, so that the alternating load is likewise intensively increased.

The described press of the invention therefore combines certain noteworthy advantages in contrast to the known constructions, it is more economical and easier to assemble, easier to transport, easier to 'preload and can be preloaded to a greater value, and furthermore, exhibits a smaller alternating load which is required for a reduced danger of rupture than the constructions in which the press frame is not preloaded by means of tensioning or preloading cables.

Finally, as shown in H0. 4 the intermediate members, namely the hollow columns 6, can be provided with guide means 20, by means of which the partially illustrated movable press punch 21 can be guided along its strokes. In this arrangement, the movable press punch 21 possesses a number of arm members 22, the sliding surfaces 23 of which can slide along the sliding surface 24 of the associated guide means 20. ln this manner, there is achieved a reliable guiding of the movable press punch 21 notwithstanding the use oftensioning cables.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

What is claimed:

1. A press comprising a press frame formed ofa lower yoke and an upper yoke and intermediate members for interconnecting said lower yoke with said upper yoke, each intermediate member being defined by a hollow column member having an internal compartment, and a plurality of preloaded tensioning cables arranged in said internal compartments of said hollow column members and which, apart from said intermediate members, hold together both of said yokes.

2..A press as defined in claim 1', wherein each yoke member is equipped with a throughpassage opening which substantially corresponds in diameter to that of said internal compartment of said hollow column members and throu h which the tensioning cables are passed, and tensioning p ate members arranged at the outside of said yokes for retaining said tensioning cables.

3. A press as defined in claim 1, further including a movable press punch mounted at said press frame, guide means arranged at said hollow column members and serving to guide said movable press punch of the press.

4. A press as defined in claim I, wherein each of said plurality of preloaded tensioning cables can be separately preloaded and independently of the other tensioning cables.

5. A press comprising a press frame formed ofa lower yoke and an upper yoke, intermediate members for interconnecting said lower yoke and said up er yoke, each intermediate member comprising a hollow column member having an internal compartment extending between opposed ends of each associated hollow column member, and a plurality of preloaded tensioning cables arranged in the internal compartment of at least one of said hollow column members, said preloaded tensioning cables being in a form of separate cable members of finite length which extend in spaced relationship from one another between said opposed ends of said at least one hollow column member, said preloaded tensioning cables serving to hold together both of said yokes. 

1. A press comprising a press frame formed of a lower yoke and an upper yoke and intermediate members for interconnecting said lower yoke with said upper yoke, each intermediate member being defined by a hollow column member having an internal compartment, and a plurality of preloaded tensioning cables arranged in said internal compartments of said hollow column members and which, apart from said intermediate members, hold together both of said yokes.
 2. A press as defined in claim 1, wherein each yoke member is equipped with a throughpassage opening which substantially corresponds in diameter to that of said internal compartment of said hollow column members and through which the tensioning cables are passed, and tensioning plate members arranged at the outside of said yokes for retaining said tensioning cables.
 3. A press as defined in claim 1, further including a movable press punch mounted at said press frame, guide means arranged at said hollow column members and serving to guide said movable press punch of the press.
 4. A press as defined in claim 1, wherein each of said plurality of preloaded tensioning cables can be separately preloaded and independently of the other tensioning cables.
 5. A press comprising a press frame formed of a lower yoke and an upper yoke, intermediate members for interconnecting said lower yoke and said upper yoke, each intermediate member comprising a hollow column member having an internal compartment extending between opposed ends of each associated hollow column member, and a plurality of preloaded tensioning cables arranged in the internal compartment of at least one of said hollow column members, said preloaded tensioning cables being in a form of separate cable members of finite length which extend in spaced relationship from one another between said opposed ends of said at least one hollow column member, said preloaded tensioning cables serving to hold together both of said yokes. 